Handbrakes on JR cars

Okay. I've increased the number of hoppers to 53, which means the train is now 5180 tons. All other factors remain the same - number of locos, same location, etc.
I release the train brake, put on the sander, and increase the throttle to notch 2. The train goes to 1mph and back down to 0 - obviously the slack un-bunching. I increase to notch 3, and the train begins to move, and 4, then we pick up speed. This is odd - but there are a couple reasons why this run might be better than the original time I tried starting on this grade.
Would mixing the YN2 and stealth locomotives affect this? That is what I did originally, while this run was 3 YN2s.
Another factor might be train length. This train was about half a mile, while the other one was about a mile, with many empty cars.
Well, it seems to work anyway. I'll try again with the original train.

OK - this train has the same makeup as the original I was having problems with. 3 engines - the train is 4832 tones this time - the cars must be loaded differently.
Released brake, started sanding, put throttle to 3, and the train doesn't move. I increase the throttle to 4, and then to 5, and it still doesn't move. I think the train length has something to do with this - as mentioned before this train is nearly a mile long. I couldn't get this moving even in notch 7.

Summary:
3 engines, 5180 tons, 0.5% grade, half-mile train - moves
3 engines, 4832 tons, 0.5% grade, mile-long train - doesn't move

not really. at this point they should be able to move that tonnage in any case presented even with no sand. try switching to that engine spec i mentioned and while you are in there see if the mass reads 166015 as it should.

Okay. I tried changing the mass and changing the espec kuid. This train, and this train only, still doesn't move? Could it be that this is a train spawned in via quick drive and then instantloaded?

Hi Justin,

It turns out that last few brakes were taking forever pop off after releasing the automatic. At any rate, you were correct; the handbrakes had nothing to do with it.

Thank you for the feedback!